In numerous applications, bulk quantities of material are required to be dispensed into containers for distribution to a consuming public. For example, in the fish processing industry, portions of butchered fish having their heads, fins, and entrails removed are often commercially distributed in hermetically sealed cans. The result is a conveniently sized product having a relatively long storage life. Because government regulations set maximum acceptable deviations between the actual and advertised product weights, it is necessary to ensure that some minimum weight of the butchered fish is inserted into each can. Given the relatively high volume of cans processed in this industry, even slight variations in container weight over the acceptable minimum are undesirable. More particularly, over the course of a production run, these weight variations cumulatively represent a significant raw material cost to the processor.
In addition to the raw material cost involved in the production of "overweight" cans, several inefficiencies in the speed of processing are typically present in conventional container filling systems. For example, if the weight of the initial portion of butchered fish introduced into a can is below the level accepted by government regulation, an additional operation is required to bring it up to weight. This process is both time consuming and costly, particularly where the weight of a significant percentage of filled cans must be adjusted. Another inefficiency results when the container filling system experiences inherent delays caused, for example, by the inequality of time required to perform various sequential operations. As will be appreciated, in applications where millions of containers are to be filled, even slight delays in the time required to process a single container presents substantial inefficiencies.
Although its influence on a processing industry may be less direct than the inefficiencies noted above, in certain applications the dispensed material may vary considerably in attractiveness from one container to the next. For example, when butchered fish are canned with conventional equipment, large, unattractive pieces of skin may be left exposed on the upper surface of some cans when opened. In addition, the orientation of the meat, or direction of its grain, may vary considerably throughout the can, failing to present the image of a substantially uniform, single piece of meat.
Lastly, the incidental presence of skin or bones around the flange of the can may prevent the can from being properly sealed. As will be appreciated, the resulting seam defect prevents a vacuum from being maintained within the can and will eventually contribute to the spoilage of the contents. Because of the health hazard presented by such spoilage, the production of even a small percentage of containers with seam defects is to be avoided. In light of these observations, there has been a need to produce a system for use in the high-speed filling of containers with accurate weights and volumes of material, while simultaneously providing a more attractive and safe container fill.
In response to the need, applicants of the present invention developed a container filling system that is described in U.S. Pat. No. 4,893,660. A modification of that system for introducing filler material of an amorphous nature into containers is described in U.S. Pat. No. 4,961,446. Although such systems provided more desirable high-speed filling of containers compared to prior systems, they did not take full advantage of their design and were less than satisfactory in addressing the entirety of the problems associated with the prior devices. Accordingly, there continues to be a need for a system that would address each of the prior problems for use in high-speed filling of containers with accurate weights and volumes of material.